Conversion of hydrocarbon oils



Aug. 16, 1938. K. SWARTWOOD CONVERSION OF HYDROCARBON OILS Original Filed Feb. 16, 1934 FURNACE 33 FURNACE 24 FURNACE l0 INVENTOR KENNETH s TWOOD TORNEY Patented Aug. 16, 1938 PATENT OFFICE CONVERSION OF HYDROC'ARBON OILS- Kenneth Swartwood, Chicago, Ill, assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application February 16, 1934, Serial No. 711,518 Renewed January 21, 1938 9 Claims.

This invention particularly refers to an improved process for the fractional distillation of hydrocarbon oils of relatively wide boiling range, such as crude petroleum, for example, whereby it is separated into selected fractions of different boiling characteristics, accompanied by the pyrolytic conversion of the total components of the charging stock, with the exception of gasoline fractions of good anti-knock value, each selected fraction being subjected to the independently controlled conversion conditions best suited to the production of the desired products therefrom, while intermediate conversion products of the process are subjected to the conditions best suited for their further conversion, together with corresponding fractions of the charging stock.

In the present invention the high boiling components of the charging stock are subjected to independently controlled relatively mild conversion conditions regulated to effect the production therefrom of a good quality liquid residue, suitable as fuel oil, while the intermediate or low boiling fractions of the charging stock, as well as intermediate conversion products resulting from fractionation of the total vaporous conversion products of the process, are subjected to more severe conversion conditions regulated to effect the production of high yields of low boiling distillate, such as motor fuel of high anti-knock value, and minor yields of residual products which may be recovered as liquids or may, when desired, be reduced to substantially dry coke within the system.

In case the charging stock contains motor fuel or motor fuel fractions of satisfactory anti-knock value it may be recovered, either alone or together with the motor fuel conversion products of the process, while any components of the charging stock within the range of motor fuel but of poor anti-knock value may be subjected to further conversion in the same system, preferably together with somewhat higher boiling componcuts of the charging stock, under conditions regulated to effect a substantial improvement in their motor fuel characteristics, particularly with respect to their anti-knock value, without excessively altering their boiling range.

It is also within the scope of the invention, when desired, to subject selected low boiling fractions of the intermediate conversion products of the process to conversion, together with intermediate and/or low boiling fractions of the charging stock while subjecting the higher boiling intermediate conversion products to independently controlled less severe conversion con-- ditions in a separate conversion zone of the same system.

One embodiment of the present invention comprises subjecting hydrocarbon oil charging stock of relatively wide boiling range, such as crude petroleum, topped crude and the like, to fractional distillation whereby it is separated into selected low boiling and high boiling fractions, subjecting the high boiling fractions to relatively mild conversion conditions of elevated temperature and superatmospheric pressure in a heating coil, introducing the heated products into a reduced pressure vaporizing chamber wherein their vaporous components are separated from the residual liquid, withdrawing the latter from the system, subjecting the vaporous conversion products to fractionation, together with the low boiling fractions of the charging stock, for the formation of reflux condensate, separating the reflux condensate into selected low boiling and high boiling fractions, subjecting the latter to conversion temperature at superatmospheric pressure in a separate heating coil and communicating reaction chamber, subjecting the low boiling reflux condensate to independently controlled conversion conditions of elevated temperature and superatmospheric pressure in another separate heating coil, commingling the hot conversion products from both of the last mentioned conversion stages of the process, separating the resulting vaporous and liquid conversion products in another reduced pressure vaporizing chamber, subjecting the vaporous conversion products from said last mentioned conversion stages of the system to said fractionation, subjecting fractionated vapors of the desired end boiling point to condensation and recovering the resulting distillate.

Various modifications of the specific embodiment above described which are within the scope of the present invention are illustrated in the accompanying drawing and will be described in connection with the following description of the drawing. The drawing is diagrammatic and is intended to illustrate one specific form of apparatus for carrying out the invention, together with some of the important modifications there- Zof which are within the scope of the invention.

Referring to the drawing, hydrocarbon oil charging stock for the process, which may comprise any desired oil of relatively wide boiling range, specifically including such oils as crude petroleum, topped crude and the like, may be heated to the desired distillation temperature, for example, by means of heat recovered from within the system or from any suitable external source or by any other well known means (not shown), and the heated charging stock is supplied through line i and valve 2 into distilling and fractionating column 3 wherein it may be separated into selected low boiling, intermediate and high boiling fractions. Any desired pressure ranging from subatmospheric to substantial superatmospheric pressure may be employed in column 3 and, when desired, heating of the charging stock may be accomplished at a substantially greater pressure than that employed in the fractionating column, although the charging stock is preferably not subjected, prior to its fractional distillation, to temperature and pressure conditions sufficiently severe to effect any appreciable pyrolytic conversion thereof.

The high boiling components of the charging stock, ordinarily comprising components thereof which cannot be subjected to sufiiciently severe conversion conditions to produce high yields of good quality motor fuel without the production of excessive yields of less desirable products, such as coke and gas, are withdrawn from the lower portion of column 3 through line 4 and valve 5 to pump 3 by means of which they are supplied through line I and valve 8 to heating coil 9, wherein they are subjected to a. relatively mild conversion temperature, preferably at substantially superatmospheric pressure, by means of heat supplied from a furnace of any suitable form. The conditions employed in heating coil 9 are preferably regulated to effect the production of a substantial yield of good quality residual liquid conversion products suitable as fuel oil, which latter are separated from the vaporous conversion products in a reduced pressure vaporizing chamber [3 to which the heated products from heating coil 9 are supplied through line H and valve l2. The non-vaporous residual liquid is withdrawn from chamber l3 through line [4 and valve l to cooling (not shown) and storage or to any desired further treatment. The vaporous products pass from chamber i3 through line 56 and valve H to commingle with other vaporous conversion products of the process and be subjected to fractionation therewith, as will be later more fully described.

Selected intermediate fractions of the charging stock, preferably comprising gas oil and including, when desired, any lower boiling components of the charging stock such as kerosene or kerosene distillate as well as, when desired, motor fuel or high boiling motor fuel fractions of poor anti-knock value, may be withdrawn as one or a plurality of suitable side streams from column 3, for example, through line I3 and valve I9 to pump 29 by means of which they are supplied through line 2! and valve 22 to heating coil 23. A furnace 24 of any suitable form supplies the required heat to the oil passing through heating coil 23 to bring it to the desired conversion temperature, preferably at a substantial superatmospheric pressure. The heated products are discharged from heating coil 23 through line 25 and may pass, all or in part, either through line 26, valve 21 and line 34 into reaction chamber 28 or to any other desired point in this zone (not shown), or may be directed, all or in part, into vaporizing chamber 29 at any desired point such as, for example, through line 39 and valve 3| into the lower portion of this zone or through line 30' and valve 3| into the upper portion of the chamber.

Heating coil 32 is located within a furnace 33 of any suitable form and reflux condensate supplied to this zone, as will be later more fully described, is heated to the desired conversion temperature, preferably at a substantial superatmospheric pressure and is discharged through line 34 and valve 35 into reaction chamber 28.

Chamber 28 is also preferably maintained at a substantial superatmospheric pressure and, although not indicated in the drawing, is preferably well insulated to prevent the excessive loss of heat by radiation so that conversion of the heated products supplied to this zone, and more particularly their vaporous components, may continue therein. In the case here illustrated, both vaporous and liquid products are discharged from the lower portion of chamber 28 through line 35 and valve 37 into vaporizing chamber 29.

Chamber 29 is preferably operated at a substantially reduced pressure relative to that employed in the reaction chamber, by means of which further vaporization of the liquid conversion products supplied to this zone is accomplished. Residual liquid remaining unvaporized in chamber 29 may be withdrawn therefrom through line 38 and valve 39 to storage or to any desired further treatment or, when desired, conditions may be so controlled in chamber 29 that the residual conversion products of the process are reduced therein to substantially dry coke. When desired, in case the process is operated for the production of coke as the residual product of the process, a plurality of coking chambers, similar to chamber 29 but not illustrated, may be employed and may be simultaneously operated or, preferably, are alternately operated and cleaned and prepared for further operation. Vaporous products pass fom the upper portion of chamber 29 through line 40 and valve 4! into tarseparator 42, preferably commingling in line 40 with the vaporous products from chamber l3.

Rough fractionating means, baffles or any other suitable means may be employed in tar-separator 42 for removing tars and similar high boiling components or entrained liquids from the vapors from chambers l3 and 29 or partial cooling of the vapors by suitable heat exchange (not shown) may be employed for the same purpose. The tars and similar high boiling materials are withdrawn from tar-separator 42 through line 43 and are preferably returned through valve 44 to chamber 29. Vaporous products escaping condensation in tar-separator 42 pass therefrom through line 45 and valve 46 to fractionation in fractionator 41.

The components of the vaporous products supplied to fractionator 41 boiling above the range of the desired final light distillate product of the process are condensed in this zone as reflux condensate. The total reflux condensate may, when desired, be withdrawn from the lower portion of the fractionator through line 48 and valve 49 to pump 50 by means of which it may be returned through line 5| and valve 52 to further conversion in heating coil 32 or, when desired, the reflux condensate may be separated within the fractionator into selected low boiling and high boiling fractions, the latter being returned by means of line 48, valve 49, pump 50, line 5|, and valve 52 to further conversion in heating coil 32 while the low boiling fractions may be withdrawn as one or a plurality of suitable side streams from the fractionator, for example through line 53 and valve 54, to pump 55 by means of which they are returned through line 56, valve 51 and line 2| to further conversion in heating coil 23.

Fractionated vapors of the desired end boiling point are withdrawn from the upper portion of fractionator 4'! through line 58 and valve 59 and are subjected to condensation and cooling in condenser 60. The resulting distillate and gas passes through line BI and valve 62 to collection and separation in receiver 63. Uncondensable gas may be released from the receiver through line 64 and valve 65. Distillate may be withdrawn from receiver 63 through line 66 and valve 61 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 63 may be recirculated, by well known means (not shown), to the upper portion of fractionator 41 toserve as a cooling and refluxing medium to assist fractionation of the vaporous products in this zone and to maintain the desired vapor outlet temperature from the fractionator.

When the selected low boiling fractions of the charging stock comprise substantially only motor fuel or motor fuel fractions, of satisfactory antiknock value and other motor fuel characteristics, they may be subjected to condensation and collected, together with the motor fuel conversion product of the process from fractionator 41, by supplying them from the upper portion of column 3 through line. 68, line 69 and valve 10 to condenser 60. When the selected low boiling fractions of the charging stock contain motor fuel of satisfactory characteristics as well as somewhat higher boiling materials they are preferably supplied through line H and valve 72 to fractionator 4'! wherein their motor fuel components may c'ommingle with the overhead vaporous stream irom the fractionator, to be condensed and collected in receiver 63, while their high boiling components commingle with the reflux condensate formed in fractionator 41 to be subjected to further conversion therewith. The latter method of operation is particularly desirable in case low boiling fractions of the reflux condensate are returned, as already described, to heating coil 23 for further conversion. In case the total reflux condensate from fractionator 41 is subjected to further conversion in heating coil 32 fractionation may, when desired, be so controlled in column 3 that any components of the charging stock such as naphtha, kerosene or kerosene distillate and the like are withdrawn from this zone, together with the intermediate fractions of the charging stock supplied to heating coil 23, as previously described; This last described method of operation may also be employed in case the charging stock contains no appreciable quantity of motor fuel or motor fuel fractions of satisfactory anti-knock value, in which case substantially only gases may comprise the low boiling fractions of the charging stock supplied, as previously described, to condenser E0 or to fractionator 41, the normally liquid, low boiling components of the charging stock being supplied, as previously described, from column 3 to heating coil 23. It is, of course, also within the scope of the invention, when desired, to subject selected low boiling fractions of the charging stock from column 3 to separate condensation and collection.

In a process such as illustrated and above described, the preferred range of operating conditions may be approximately as follows:

Relatively mild conversion conditions utilizing a temperature of from 800to 900 F., or thereabouts, and a pressure of from 100 to 500 pounds, or thereabouts, per square inch, as measured at the outlet from the heating coil, may be employed for the treatment of the high boiling fractions of the charging stock, the pressure preferably being reduced in the vaporizing chamber following the heating coil of this stage of the process to within the range of substantially atmospheric to 100 pounds, or thereabouts, per square inch superatmospheric pressure. The heating coil to which the reflux condensate from the fractionator of the cracking system is supplied preferably employs a somewhat higher conversion temperature of the order of 850 to 950 F., or thereabouts, preferably with a superatmospheric pressure, measured at the outlet from the heating coil, of from 100 to 500 pounds, or more, per square inch. A substantially equalized or somewhat reduced pressure may be employed in the succeeding reaction chamber and the vaporizing chamber of the cracking system preferably employs a substantially reduced pressure, relative to that employed in the reaction chamber, ranging, for example, from 100 pounds, or thereabouts, per square inch, to substantially atmospheric pressure. The pressures employed in the fractionating, condensing and collecting portions of the cracking system may be substantially equalized or somewhat reduced relative to the pressure employed in the preceding vaporizing chambers. The heating coil employed for the treatment of the intermediate fractions of the charging stock and, when desired, low boiling fractions of the reflux condensate may employ an outlet conversion temperature ranging, for example, from 900 to 1,000 E, or thereabouts, preferably with a superatmospheric pressure at this point in the system of from 200 to 800 pounds, or more, per square inch, although, when desired, lower pressures down to substantially atmospheric may be employed in this zone, in which case the heated products from this stage of the process are preferably discharged into the vaporizing chamber of the cracking system. As previously indicated, any desired pressure ranging from subatmospheric or substantially atmospheric to 200 pounds, or more, per square inch, superatmospheric pressure may be employed in the fractional distilling stage of the process to which the charging stock is supplied.

As a specific example of an operation of the process of the present invention utilizing as charging stock a Smackover crude of about 18.4

A. P. I. gravity containing approximately 5% of material boiling up to 437 F., the charging stock is heated to a temperature of approximately 725 F. and is subjected to fractional distillation at substantially atmospheric pressure. Approximately 45% of the charging stock, comprising its high boiling fractions, are subjected to a conversion temperature of approximately 850 F. in a heating coil employing an outlet pressure of approximately 200 pounds per square inch. The heated products are introduced into a vaporizing chamber operated at a reduced superatmospheric pressure of approximately pounds per square inch, vaporous products from which are supplied to the vaporizing and coking chamber of the other cracking stage of the system. The total lower boiling fractions of the charging stock are supplied to the fractionator of the cracking system wherein they are separated, together with the reflux condensate resulting from fractionation of the vaporous conversion products supplied to this zone, into low boiling fractions, having a boiling range of approximately 400 to 600 F., and higher boiling fractions. The latter are subjected in a heating coil to an outlet conversion temperature of approximately 950 F. at a superatmospheric pressure of about 350 pounds per square inch and the heated products are introduced into a reaction chamber operated at substantially the same pressure. The low boiling fractions of the reflux condensate and charging stock, from the fractionator of the cracking system, are subjected in a separate heating coil to an outlet conversion temperature of approximately 980 F. at a superatmospheric pressure of about 700 pounds per square inch. Vaporous and liquid conversion products from the reaction chamber are discharged into a reduced pressure vaporizing and coking chamber and the highly heated products from the last mentioned heating coil are also introduced into the coking chamber in such a manner that they come into direct contact with the residual material in this zone, assisting its reduction to coke. Vaporous products from the coking chamber are supplied to the fractionator, the overhead Vaporous product from which is subjected to condensation and the resulting distillate collected as the motor fuel product of the process. This operation may yield, per barrel of charging stock, about 47% of 400 F. end point motor fuel of good anti-knock value, approximately 30% of premium fuel oil and about 45 pounds of low volatile coke, the remainder being chargeable principally to uncondensable gas.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oil wherein hydrocarbon oil is subjected to conversion temperature at superatmospheric pressure in a heating coil and communicating reaction chamber, the resulting vaporous and liquid conversion products introduced into a reduced pressure vaporizing chamber, wherein the liquid conversion products are subjected to further vaporization and the vapors separated from the non-Vaporous residue, the improvement which comprises subjecting hydrocarbon oil charging stock for the process to fractional distillation, whereby it is separated into selected low boiling and higher boiling fractions, subjecting the high boiling fractions of the charging stock to relatively mild conversion conditions of elevated temperature and superatmospheric pressure in a second heating coil, introducing the resulting products into a separate reduced pressure vaporizing chamber wherein their Vaporous components separate from the residual liquid, withdrawing the latter from the system, heating low boiling fractions of the charging stock in a third heating coil to higher cracking temperature than said high boiling fractions, fractionating resultant vapors in admixture with vapors from said separate chamber for the formation of reflux condensate, subjecting fractionated vapors of the desired end boiling point to condensation, recovering the resulting distillate, separating the reflux condensate into selected low boiling and high boiling fractions, returning the latter to the first mentioned heating coil for further conversion, supplying the low boiling fractions of the reflux condensate to said third coil for treatment therein together with selected low boiling fractions of the charging stock and commingling the resulting products from the third coil, prior to separation of vapors therefrom, with products from the first mentioned heating coil, the process being further characterized in that the heated products from the third heating coil are introduced into direct contact with the residual material in the first mentioned reduced pressure vaporizing chamber for the purpose of assisting the reduction of said residual material to coke.

2. A process of the character defined in claim 1 wherein any motor fuel components of the charging stock of satisfactory anti-knock value are recovered Without being subjected to pyrolytic con version.

3. A process for the conversion of hydrocarbon charging oil containing residual portions of petroleum which comprises partially distilling said charging oil to form a distillate fraction and hottoms, subjecting said bottoms in a heating coil to relatively mild cracking conditions regulated to produce fuel oil therefrom, separating the heated products in an enlarged chamber into vapors and residual liquid suitable as fuel oil, recovering said liquid as a product of the process, fractionating the vapors and combining resultant reflux condensate with said distillate fraction, subjecting the commingled materials in a second heating coil to more drastic cracking than said bottoms in the first-named coil and subsequently distilling the same to coke in a second enlarged chamber, and fractionating and condensing the vapors evolved in said second chamber.

4. A process for the conversion of hydrocarbon charging oil containing residual portions of petroleum which comprises partially distilling said charging oil to form a distillate fraction and bottoms, subjecting said bottoms in a heating coil to relatively mild cracking conditions regulated to produce fuel oil therefrom, separating the heated products in an enlarged chamber into vapors and residual liquid suitable as fuel oil, recovering said liquid as a product of the process, fractionating the vapors and combining resultant reflux condensate with said distillate fraction, subjecting the commingled materials in a second heating coil to more drastic cracking than said bottoms in the first-named coil and subsequently distilling the same to coke in a second enlarged chamber, fractionating resultant vapors together with the first-mentioned vapors whereby portions thereof are incorporated into said reflux condensate and supplied to said second coil, and finally condensing the fractionated vapors.

5. A process for the conversion of hydrocarbon charging oil containing residual portions of petroleum which comprises partially distilling said charging oil to form a distillate fraction and hottoms, subjecting said bottoms in a heating coil to relatively mild cracking conditions regulated to produce fuel oil therefrom, separating the heated products in an enlarged chamber into vapors and residual liquid suitable as fuel oil, recovering said liquid as a product of the process, fractionating the vapors and combined resultant reflux condensate with said distillate fraction, subjecting the commingled materials in a second heating coil to more drastic cracking than said bottoms in the first-named coil and subsequently distilling the same to coke in a second enlarged chamber, fractionating the vapors evolved in the second chamber to form additional reflux condensate and subjecting such additional condensate in a third heating coil to independently controlled cracking conditions of temperature and pressure, introducing the heated products thus formed to said second chamber for reduction to coke therein, and finally condensing the fractionated vapors.

6. The process as defined in claim 5 further characterized in that said vapors evolved in the second chamber are fractionated in admixture with the first-named vapors.

7. The process as defined in claim'5 further characterized in that said additional condensate is separated from the admixed vapors as a primary reflux of higher boiling point than the firstmentioned reflux condensate and is subjected in the third heating coil to milder cracking than said commingled materials in the second heating coil.

8. A process for the conversion of hydrocarbon charging oil containing residual portions of petroleum which comprises partially distilling said charging oil to form a distillate fraction and bottoms, simultaneously fractionating cracked vapors, formed as hereinafter set forth, and separating therefrom a relatively heavy reflux condensate and a lighter reflux condensate, subjecting said bottoms in a heating coil to relatively mild cracking conditions regulated to produce fuel oil therefrom and separating the fuel oil from vaporous conversion products in an enlarged chamber, withdrawing the fuel oil from the chamber and recovering the same as a product of the process, subjecting the heavy reflux condensate in a second heating coil to more drastic cracking than said bottoms in the first-named coil and introducing the resultant products into a second enlarged chamber, combining the lighter reflux condensate with said distillate fraction and subjecting the resultant mixture in a third heating coil to more drastic cracking than the heavy reflux condensate in the second coil, introducing the heated products formed in the third coil to said second chamber and therein distilling the commingled products to coke, supplying vaporous conversion products from the first-mentioned chamber and from said second chamber to the aforesaid fractionating step as said cracked vapors, and finally condensing the fractionated vapors.

9. A conversion process which comprises partially distilling and fractionating crude petroleum to form crude oil bottoms, a gasoline fraction of satisfactory anti-knock value and an intermediate distillate fraction containing the low antiknock gasoline components of the crude, recovering said gasoline fraction, simultaneously fractionating cracked vapors, formed as hereinafter set forth, and separating therefrom a relatively heavy reflux condensate and a lighter reflux condensate, subjecting said bottoms in a heating coil to relatively mild cracking conditions regulated to produce fuel oil therefrom and separating the fuel oil from vaporous conversion products in an enlarged chamber, withdrawing the fuel oil from the chamber and recovering the same as a product of the process, subjecting the heavy reflux condensate in a second heating coil to more drastic cracking than said bottoms in the first-named coil and introducing the resultant products into a second enlarged chamber, combining the lighter reflux condensate with said distillate fraction and subjecting the resultant mixture in a third heating coil to more drastic cracking than the heavy reflux condensate in the second coil, introducing the heated products formed in the third coil to said second chamber and therein distilling the commingled products to coke, supplying vaporous conversion products from the first-mentioned chamber and from said second chamber to the aforesaid fractionating step as said cracked vapors, and finally condensing the fractionated vapors,

KENNETH SWAR'I'WOOD. 

